Abstract: Upgrade of aging harbor breakwaters is a worldwide problem, whose urgency is enhanced by the effects
of climate change on coastal areas. In this context, the present work contributes to improve current
understanding of the hydraulic response of damaged and upgraded rubble-mound breakwaters, providing also
a methodology for the implementation of an ad-hoc prediction tool based on numerical simulations. The
numerical model IH2VOF, which was calibrated using experimental data, proved to be a valid tool for the
study of wave overtopping phenomena of structures with irregular armor slope or additional armor layers.
The results confirmed that also for the non-conventional tested structures the wave sequence significantly
affects the uncertainty of wave overtopping estimates when low-energy sea states are considered, more than
the time series length. Site-specific formulas for the assessment of both mean wave overtopping discharge
and probability were defined to overcome the limits of state-of-the-art formulations. Finally, traditional
formulations for the description of the individual wave overtopping volumes based on the two-parameters
Weibull distribution can be applied also to damaged and upgraded breakwaters.
